# Templates { #templates }

You can use any template engine you want with **FastAPI**.

A common choice is Jinja2, the same one used by Flask and other tools.

There are utilities to configure it easily that you can use directly in your **FastAPI** application (provided by Starlette).

## Install dependencies { #install-dependencies }

Make sure you create a [virtual environment](../virtual-environments.md), activate it, and install `jinja2`:

  {{.HelpName}} {{if .VisibleFlags}}[FLAGS] {{end}}DIR{1...64} DIR{65...128}

DIR:
  DIR points to a directory on a filesystem. When you want to combine
  multiple drives into a single large system, pass one directory per
  filesystem separated by space. You may also use a '...' convention
  to abbreviate the directory arguments. Remote directories in a
  distributed setup are encoded as HTTP(s) URIs.
{{if .VisibleFlags}}
FLAGS:

   *       is used to construct the sample instances. In case of tie, the candidate constructors or
   *       factories are tried one after another until one can be used to construct sample
   *       instances.
   *   <li>For the constructor or static factory method used to construct instances, it's checked

    result = 31 * result + proxy.hashCode()
    result = 31 * result + socketAddress.hashCode()
    return result
  }

  /**
   * Returns a string with the URL hostname, socket IP address, and socket port, like one of these:
   *
   *  * `example.com:80 at 1.2.3.4:8888`
   *  * `example.com:443 via proxy [::1]:8888`
   *
   * This omits duplicate information when possible.
   */
  override fun toString(): String =

   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as
   * {@code requireNonNull}: Our use case is the one in which {@code T} has parametric nullness—and
   * thus its value may be legitimately {@code null}.)
   */
  @ParametricNullness
  @SuppressWarnings("nullness")

 * version of this interface will be made to <i>extend</i> {@code java.util.function.Predicate}, so
 * that conversion will be necessary in only one direction. At that time, this interface will be
 * officially discouraged.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@GwtCompatible
public interface Predicate<T extends @Nullable Object> {
  /**

import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A multimap which forwards all its method calls to another multimap. Subclasses should override
 * one or more methods to modify the behavior of the backing multimap as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

import java.util.Collection;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * A set which forwards all its method calls to another set. Subclasses should override one or more
 * methods to modify the behavior of the backing set as desired per the <a
 * href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

   * to get rid of, and {@code @NonNull} would be wrong for our use case for the same reason as
   * {@code requireNonNull}: Our use case is the one in which {@code T} has parametric nullness—and
   * thus its value may be legitimately {@code null}.)
   */
  @ParametricNullness
  @SuppressWarnings("nullness")

   * Notes on EnumSet and <E extends Enum<E>>:
   *
   * This class isn't an arbitrary ForwardingImmutableSet because we need to
   * know that calling {@code clone()} during deserialization will return an
   * object that no one else has a reference to, allowing us to guarantee
   * immutability. Hence, we support only {@link EnumSet}.
   */
  private final transient EnumSet<E> delegate;

  private ImmutableEnumSet(EnumSet<E> delegate) {